How Citrix HDX user policies dictate USB redirection Behaviour:
Here are some points you must understand:
• The VDA in HVD and the client (VXC 6215) have separate USB rules.
• Enabling a device to redirect that typically should not redirect involves allowing the device on the VDA and the endpoint.
• Disabling a device from redirecting only requires configuring the VDA or the endpoint.
The USB rules for VDA in HVD is configured in Xendesktop DDC Desktop Studio, HDX Policy -> Users -> "Client USB Device Redirection" and "Client USB Device Redirection Rules", These configurations and rules will be then pushed into HVD registry settings for VDA in the following locations for taking effect:
The USB rules for VXC 6215 is influenced by the wlx.ini parameter ICAAllowUSB (whenever is configured, implictly DENY ALL), and VXME(UC Firmware, whenever installed, implictly DENY ALL), the rule can also be found from following location in vxc 6215:
Please refer to the background and configuration link to understand how to configure vxc 6215 to allow ALL usb redirections or only allow specific usb device redirections.
USB Mass Storage Devices - Client Drive Mapping vs USB Redirection
For mass storage devices only, remote access is also available through client drive mapping, where the drives on the user device (VXC 6215) are automatically mapped to drive letters on the virtual desktop when users log on. The drives are displayed as shared folders with mapped drive letters. To configure client drive mapping, use the Client removable drives setting in the File Redirection Policy Settings section of the ICA Policy Settings.
The main differences between the two types of remoting policy is that for Client drive mapping, the HVD OS see it as a remote drive; and for USB Redirection, the HVD OS gain visibility to the actual USB device, and manage it as USB Removable Storage Devices, and furthemore:
Client drive mapping
Enabled by default
Read-only access configurable
Safe to remove device during a session
Yes, provided users follow operating system recommendations for safe removal
If both client drive mapping and the USB rule are enabled, then if a mass storage device is inserted before a session starts, it will be redirected using client drive mapping first, before being considered for redirection through USB support. If it is inserted after a session has started, it will be considered for redirection using USB support before client drive mapping.
Important Note: These two different ways of supporting USB Mass Storage Devices often create confusion and inconsisten USB experience if users do know understand their difference. We have also observed that not all USB Mass Storage Devices are working with Client Drive Mapping, specially the USB sticks equal or larger than 16 GB at the time of writing this post. However, USB Redirection does work with most of the USB sticks. Because Client Drive Mapping is enabled by default, when user is able to use one of their USB sticks in HVD, but some other USB sticks are not working, the user is under the impression that USB redirection is enabled properly but somehow not working properly. However in fact, the USB redirection is not enabled at all in the system. Please be also noted, USB keyboard, mouse, audio headse and USB webcam can also work without USB redirection. USB keyboard and mouse are always owned by the end device (VXC 6215) and the key strokes are sent into HVD via ICA session, USB headsets and webcams by default are using Citrix HDX realtime, and get presented into HVD OS as a single device as Citrix HDX audio and video.
After you have plugged in the USB device.
Event Viewer -> Applications and Services Logs -> Citrix -> USB -> Service -> Admin
As below, if you see a message about The Citrix USB Service policy disables USB Redirection, it means either USB Redirection is not enabled in Citrix HDX policy, or the policy is not pushed down to the HVD properly via DDC Desktop Studio or Active Directory GPO.